Let's come up with an amphibian race!

Well, suggest something, or let's take a shapeshifter that can transform into any unit.

Hold on. Not everything happens so quickly. The idea is great, but it needs to be developed in all directions: will it be a shapeshifter or will it disappear from the battlefield, leaving behind a "black hole" that pulls everyone around it within a certain radius, or something else – we need to think about that!